Liquid level gauge



Oct. 10' 1967 c. ANDREA LIQUID LEVEL GAUGE 2 Sheets-Sheet 1 OriginalFiled Nov. 15, 1962 v 3 1 1m 7 d 34} 2 2 3 W J g) CT F L. 1.6,. @6 66 QQ i 1 J Q MWQL @Q @U Z Oct. 10 1967 ANDREA 3,345,871

' LIQUID LEVEL GAUGE Original Filed Nov. 15, 1962 2 Sheets-Sheet z ii i7INVENTOR (777.92 0 724 7? tux/ f I United States Patent This inventionrelates generally to gauges and, more particularly, to liquid levelgauges for high pressure steam boilers and the like and the presentapplication is a continuation of my previously filed copendingapplication Ser. No. 237,882 filed Nov. 15, 1962, now abandoned.

An important object of this invention is to provide an improved liquidlevel gauge of the type having a plurality of sight windows throughwhich liquid level may be directly observed, and to incorporate thereinimproved means for sealing the transparent windows with respect to thesupporting housing in which they are arranged; improved means foreliminating stresses applied to the windows; and improved means forpreventing the development of unduly high stresses, while, nevertheless,permitting quick and simple removal and replacement of the windows whendesired.

In gauges of this type heretofore in use, the port gasketing elementsare assembled and tightened hand-tight, usually equivalent to abouttwenty foot-pounds torque. After the gauge has been subjected to steam,the sealing gasket loses some of its compression and the cap screws mayelongate due to heat expansion and the clamping load on this gasket isrelaxed. It therefore becomes necessary to retighten the cap screws ofthe gauge after the gauge has thus been warmed up to compensate for thisloss of compression on the sealing gasket.

The specifications of water level gauges for use, for

instance, in nuclear installations provide that no retorqueing orretightening of the cap screws should be necessary for properly sealingthe ports of the gauge after the unit is placed in service. This isbecause it is usually impossible or extremely ditficult to gain accessto the gauge once the boiler is in operation.

Heretofore, attempts have been made to eliminate the necessity ofretightening the gasketing elements by the use of a spring washerinterposed between the cover plate and the gauge glass. Howeventhisproved to be unsatisfactory, since the total force required to seat thegasket for sealing would be transmitted through the glass. Thissometimes resulted in shattering the gauge glass. Thisv tendency toshatter the glass is heightened if cycling occurs or the bolts aretightened unevenly.

It is therefore a primary object of this invention to provide animproved gauge of the so-called loose window type in which the sealingforce is completely removed from the gauge glass and wherein the sealingforce is transmitted through a separate, axially movable, spring-loadedthrust transmitting member which functions both to position the glassand to yiel-dably compress the sealing gasket means. After aconsiderable period of testing at boiler pressures of from 2000 to 2700p.s.i., it has been found that with a gauge constructed inaccordancewith this invention there was not one case of glass shattering; thegauge was insensitive to cycling; and the useful life of the gauge wasmaterially lengthened over the useful life of previous gauges of thisgeneral type. Also, the necessity for'retightening the gasketingelements is entirely eliminated.

These desirable advantages are obtained by a construction comprising acombined gauge glass retainer and thrust member, a cover plate adaptedto be attached by cap screws to the gauge body, and a dished springwasher (commercially known as a Belleville washer) interposed betweenthe glass retainer and cover plate which are telescoped one within theother. When the assembly, consisting of the cover plate, spring washer,and glass retainer, is secured in place by tightening the cap screws,the spring washer is compressed or flattened so that it will act as aspring to take up any relaxation of the sealing gasket (inherent in itsconstruction or due to temperature expansion of the cap screws) andmaintain a pressure on the sealing gasket substantially equal to theoriginal pressure imposed by the torque on the cap screws. With thisconstruction the need for retightening the cap screws is eliminated, andthe pressure on the sealing gasket is applied directly thereto by theglass retainer and not through the gauge glass.

The above described principles of the invention may be embodied in aconstruction in which the cover plate is tightened by the cap screwsuntil it contacts the center plate or body of the gauge, or in which thecover plate does not contact the center plate but the cap screws aretightened to a predetermined torque, either by a torque wrench or madewrist tigh without forcing the cap screws. 7

Other objects of the invention are to provide a device of this typewhich is so reduced in the number and character of its component partsas to approach the ultimate in structural simplicity and wherein thestructural simplicity of the device creates an economy in itsmanufacture, installation and maintenance. 1

The various objects and advantages, and the novel details of acommercially practical embodiment of the invention, will become moreapparent as this description proceeds, especially when considered inconnection with the accompanying drawings, in which:

FIGURE 1 is a front elevational view of a multi-port liquid level gaugeconstructed in accordance with the present invention;

FIGURE 2 is an enlarged sectional view taken substantially on the planeindicated by line 22 in FIG- URE 1;

FIGURE 3 is a separated sectional, elevational View showing thegasketing elements more in detail; and

FIGURE 4 is a fragmentary sectional view showing the cover plateassembly out of contact with the body of the gauge.

Referring first to FIGURE 1 of the drawings, it will be noted there isshown a pair of pipes 10 terminating in flanges 11, the pipes 10 beingconnected to and communicating with a boiler, the water level of whichis to be observed. Each of the flanges 11 is associated with a matingflange 12, one of which is integral with a lower pipe 13 and the otherwhich is integral with an upper pipe or gauge loop 14. Each of the pipes13 and 14 is rigidly fixed to the gauge 15 and acts to support the sameon the boiler.

The gauge 15 comprises a center plate or body 16 (FIGURES 2 and 3)provided with a vertically extending columnar passage defining a bore17, FIGURE 2, extending longitudinally within the body or center plate16. The bore 17 is connected at its lower end of the pipe 13 and at itsupper end to the pipe or gauge loop 14.

The contents of the bore or passage 17 are visible through a pluralityof sight ports 18 in alignment with and positioned correspondingly totransversely extending apertures 19 formed in vertically spaced portionsof the body 16 in intersecting relation with the bore 17. A similarnumber of light port apertures 20 are provided at the opposite ends ofthe transverse apertures 19, as is customary in gauges of this type.

The gasketing means or elements are the same for both the sight portapertures 18 and the light port apertures 20, and it is With respect tothe maintenance of the sealing efiiciency of this gasketing means thatthe present invention particularly pertains.

On each side the body or center plate 16 is provided with a recessforming a shoulder 26 which surrounds each of the transverse apertures19. Seated on the shoulder 26 is a sealing gasket 27 which may be andpreferably is of the laminated asbestos-sheet metal type with thelaminations thereof bent to so-called chevron form in cross section.This type of gasket is commercially known as a Flexitallic gasket and isaxially resiliently compressible. Seated on the gasket 27 is aprotective gasket 28 usually of metal. A cushioning and protective disk29 of relatively resilient and tough transparent material, such as mica,is fitted over the protective gasket 28 between it and the observationwindow 30. A packing strip 31 of asbestos or the like is usuallyinterposed between the periphery of the lens or observation window 30and the glass retainer 32. The reference character 33 indicates acushion gasket made preferably of asbestos interposed between theobservation window 30 and the bottom of the recess 34 in the glassretainer 32.

The glass retainer 32 forms one part of the cover plate or frameassembly, which also comprises a cover plate part 35 of cup-shapedconstruction into which the glass retainer 32 is telescopically fitted.Interposed between these two parts is a frusto-conical or dish-shapedwasher 36. This type of washer, commercially known as a Bellevillewasher, functions as a stiff compression spring, the necessary stiffnessthereof being of course a function of the pressure which is to beretained.

The cover plate part 35 is provided with an interiorly arranged, axiallyelongated annular groove 37 adapted to mate with an exteriorly arrangedgroove 38 adapted to receive within their confronting open ends a snapring 39 which will hold the parts 32 and 35 in assembled relation butpermit relative movement in the form of axial lost motion therebetween.

The cover plate part 35 is secured to the body 16 by fastening meanssuch as .cap screws 40 which are threaded into the body 16 as indicatedat 41 in FIGURE 2. The cap screws 40 may be tightened until the coverplate 35 makes contact with the adjacent surface of the body 16, asshown in FIGURE 2, or the cover plate as shown at 35a in FIGURE 4 may beso dimensioned that it does not come in direct contact with the centerplate when the cap screws 40 are tightened to a certain torque, eitherby a torque wrench or made wrist tight by hand, without forcing the capscrews, thus leaving a space 35b between cover plate part 35a and theboy 16 of the gage.

In either event, when the cover plate assembly, including the glassretainer 32, the cover plate part 35 and the spring member 36, issecured to the body 16, the spring member 36 will be loaded or tensionedby flattening the same so as to exert a continuing pressure on the glassretainer 32 to apply a continuous sealling pressure to the sealinggasket 27. It will be noted that the edge or end portion 42 of the glassretainer 32 acts through the mica disk 29 and protective gasket 28 tocompress the sealing gasket 27 to press the latter into sealingengagement with the shoulder 26 and thus seal the sight and light ports18 and 20.

As pointed out hereinbefore, after the gauge has been subjected tosteam, the sealing gasket 27 loses some of its compression and the capscrews may elongate due to heat expansion and the clamping load on thisgasket is thus relaxed. Ordinarily, it would be necessary to retightenthe cap screws 40 to compensate for this loss of pressure on the sealinggasket. However, with this invention, the spring member or Bellevillewasher 36 is compressed and thus loaded when the cover plate assembly isinitially secured to the gauge body or center plate 16 and willcompensate for any relaxation of the sealing gasket 27 and/or screws 40and maintain the pressure on the gasketing means substantially equal tothe pressure originally imposed by the torque on the cap screws. Thus,it is unnecessary to retighten the cap screws after the gauge has beenplaced in service.

It will be noted that the glass or observation window element 30 isreceived in the recess 34 of the gasketpressurizing thrust member orglass retainer 32 and that the pressure exerted by the glass retainer 32on the sealing gasket 27 is not through the observation window, so thatthere will be no danger of shattering the observation window 30. Thus,while the observation window 30 fits snugly within the recess 34, it isrelatively loose therein because the clamping pressure on the sealinggasket 27 is imposed directly on the sealing gasket and not through theobservation window. The resiliency of the Belleville washer spring 36also tends to equalize the compressive loading peripherally of theassembly, as well as to follow any movement or distortion of the partsand thus maintain a uniform seal in all areas as well as to maintain aneffectively tight seal at all times as indicated.

While a commercially practical embodiment of the invention has beendescribed and illustrated herein somewhat in detail, it will beunderstood that various changes may be made as may come within thepurview of the accompanying claims.

What is claimed is:

1. In a liquid level gauge having a body provided with a water chamber,an observation port extending through the body from the exterior thereofand intersecting said water chamber, an observation window element forclosing said port, a sealing gasket surrounding said port and having aradially projecting portion of greater diameter than the window element,such projecting portion overlying a portion of the body radially beyondthe margins of said window element, a cover plate for securing saidwindow element in closing position over said port, and means for rigidlysecuring the cover plate to the body, that improvement which comprisesan axially rigid thrust frame surrounding the periphery of the windowelement and interposed between said cover plate and said projectingportion of the gasket, said thrust frame being of an axial depth suchthat its end toward the water chamber is substantially coplanar with thewindow element and being axially movable independently of the coverplate, and a spring member interposed between the cover plate and thethrust frame and compressively loaded to urge the thrust frame againstthe gasket and the gasket against the body independently of the windowelement.

2. A liquid level gauge as defined in claim 1 wherein said gasket isaxially compressible through a substantial distance and said springmember is of dished form.

3. In a liquid level gauge having a body provided with a water chamber,an observation port extending through the body from the exterior thereofand intersecting said water chamber, an observation window element forclosing said port, an axially compressible sealing gasket surroundingsaid port and having a radially projecting portion of greater diameterthan the window element, such projecting portion overlying a portion ofthe body radially beyond the margins of said window element, a coverplate for securing said window element in closing position over saidport, and means for rigidly securing the cover plate to the body, thatimprovement which comprises an axially rigid thrust frame surroundingthe periphery of the window element and interposed between said coverplate and said projecting portion of the gasket, said thrust frame beingaxially movable independently of the cover plate, a spring memberinterposed between the cover plate and the thrust frame andcompressively loaded to urge the thrust frame against the gasket and thegasket against the body independently of the window element, said coverplate being of cupped form and the thrust frame also being of cuppedform and slidably fitted into the cover plate, and lost motionconnecting means preventing separation of the thrust frame and coverplate but permitting relative axial movement therebetween.

4. A liquid level gauge as defined in claim 1 wherein said spring membercomprises a dished washer concentric 5 6 with said port and having itsportion of greater radius 2,882,730 4/1959 Yarnall 73331 bearing againstthe thrust frame and its portion of lesser 3 013 433 12/19 1 il et 1 7333 radius bearing against the cover plate. FOREIGN PATENTS ReferencesCited 5 555,008 7/1932 Germany. UNITED STATES PATENTS 1,051,105 1/1913Hatz LOUIS R. PRINCE, Primary Examin r- 1,335,904 4/1920 Macneir 7333()D. M. YASICH, Assistant Examiner.

2,603,090 7/1952 Brelsford 73331

1. IN A LIQUID LEVEL GUAGE HAVING A BODY PROVIDED WITH A WATER CHAMBER,AN OBSERVATION PORT EXTENDING THROUGH THE BODY FROM THE EXTERIOR THEREOFAND INTERSECTING SAID WATER CHAMBER, AN OBSERVATION WINDOW ELEMENT FORCLOSING SAID PORT, A SEALING GASKET SURROUNDING SAID PORT AND HAVING ARADIALLY PROJECTING PORTION OF GREATER DIAMETER THAN THE WINDOW ELEMENT,SUCH PROJECTING PORTION OVERLYING A PORTION OF THE BODY RADIALLY BEYONDTHE MARGINS OF SAID WINDOWS ELEMENT, A COVER PLATE FOR SECURING SAIDWINDOW ELEMENT IN CLOSING POSITION OVER SAID PORT, AND MEANS FOR RIGIDLYSECURING THE COVER PLATE TO THE BODY, THE IMPROVEMENT WHICH COMPRISES ANAXIALY RIGID THRUST